A comparison of voluntary and electrically evoked isokinetic plantar flexor torque in males

The angle-specific isokinetic torque- and power-velocity relationships of the triceps surae were examined in ten male sprint athletes aged [mean (SD)] 22.4 (3.2) years, ten non-trained adult men aged 27.4 (4.8) years and six elderly male subjects aged 68.5 (2.4) years. Normal voluntary contractions were compared with those obtained using maximal tetanic stimulation and a release technique which standardised the level of muscle activation during isokinetic contractions. When the isokinetic data was normalized to the maximum isometric torque the stimulated release contractions at 5.18-5.29 rad.s-1 produced significantly (P < 0.05) greater torque than the voluntary no-release contractions at the same angular velocity in each group of subjects. The three subject groups generated their peak power at 3.07 rad.s-1 during the voluntary no release contractions. However, with the stimulated release contractions, power had still not reached a peak at 5.29 rad.s-1, the highest angular velocity that could be tested. It appears that at higher angular velocities the triceps surae is capable of greater torque and power generation when contractions are evoked using a stimulated release technique. It is suggested that the stimulated release technique gives a more complete picture of the torque-velocity characteristics of the contractile component of the triceps surae.